From owner-freebsd-hackers Fri Nov 7 01:55:27 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id BAA22360 for hackers-outgoing; Fri, 7 Nov 1997 01:55:27 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from Campino.Informatik.RWTH-Aachen.DE (campino.Informatik.RWTH-Aachen.DE [137.226.116.240]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id BAA22348 for ; Fri, 7 Nov 1997 01:55:23 -0800 (PST) (envelope-from kuku@gilberto.physik.RWTH-Aachen.DE) Received: from gil.physik.rwth-aachen.de (gilberto.physik.rwth-aachen.de [137.226.30.2]) by Campino.Informatik.RWTH-Aachen.DE (8.8.7/RBI-Z14) with ESMTP id KAA08123 for ; Fri, 7 Nov 1997 10:55:12 +0100 (MET) Received: (from kuku@localhost) by gil.physik.rwth-aachen.de (8.8.5/8.6.9) id KAA27835 for freebsd-hackers@freefall.cdrom.com; Fri, 7 Nov 1997 10:55:19 +0100 (MET) Date: Fri, 7 Nov 1997 10:55:19 +0100 (MET) From: Christoph Kukulies Message-Id: <199711070955.KAA27835@gil.physik.rwth-aachen.de> To: freebsd-hackers@freefall.FreeBSD.org Subject: root - can root do an asm("cli")? Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk Is there a difference between what the kernel can do vs. what a root process can do with regard to priviliged instructions? In particular: can a root process do an asm("cli"); and thus block the whole system? I tried once under FreeBSD and got a bus error. May be the cause was a differnet one but when I got that bus error I thought: "Hmm, fine, so there is something running at a different ring which prevents root from doing such malign things" and was feeling safe. Now someone tells me, root can do everything and can even do that. -- Chris Christoph P. U. Kukulies kuku@gil.physik.rwth-aachen.de